Communication system with partial power source

ABSTRACT

The system of the present invention includes a conductive element, an electronic component, and a partial power source in the form of dissimilar materials. Upon contact with a conducting fluid, a voltage potential is created and the power source is completed, which activates the system. The electronic component controls the conductance between the dissimilar materials to produce a unique current signature. The system can be used in a variety of different applications, including as components of ingestible identifiers, such as may be found in ingestible event markers, e.g., pharmainformatics enabled pharmaceutical compositions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/865,508 filed Sep. 25, 2015, which is a continuation of U.S. patentapplication Ser. No. 14/341,639 filed Jul. 25, 2014, which is acontinuation of U.S. patent application Ser. No. 13/153,312 filed Jun.3, 2011, now U.S. Pat. No. 8,816,847, which is a continuation of U.S.patent application Ser. No. 12/564,017 filed Sep. 21, 2009, now U.S.Pat. No. 7,978,064, which is a continuation of U.S. patent applicationSer. No. 11/912,475 filed Jun. 23, 2008, now U.S. Pat. No. 8,847,766,which application is a 371 application of PCT Application Serial No.PCT/US06/16370 filed Apr. 28, 2006; which application pursuant to 35U.S.C. §119 (e), claims priority to the filing dates of: U.S.Provisional Patent Application Ser. No. 60/676,145 filed Apr. 28, 2005;U.S. Provisional Patent Application Ser. No. 60/694,078 filed Jun. 24,2005; U.S. Provisional Patent Application Ser. No. 60/713,680 filed Sep.1, 2005 and U.S. Provisional Patent Application Ser. No. 60/790,335filed Apr. 7, 2006; the disclosures of which are herein incorporated byreference.

FIELD

The present invention is related to systems for detection of an event.More specifically, the present disclosure includes a system thatincludes a partial power source that can be activated when in contactwith conductive liquid and is capable of controlling conductance to markan event.

BACKGROUND

Ingestible devices that include electronic circuitry have been proposedfor use in a variety of different medical applications, including bothdiagnostic and therapeutic applications. These devices typically requirean internal power supply for operation. Examples of such ingestibledevices are ingestible electronic capsules which collect data as theypass through the body, and transmit the data to an external receiversystem. An example of this type of electronic capsule is an in-vivovideo camera. The swallowable capsule includes a camera system and anoptical system for imaging an area of interest onto the camera system.The transmitter transmits the video output of the camera system and thereception system receives the transmitted video output. Other examplesinclude an ingestible imaging device, which has an internal and selfcontained power source, which obtains images from within body lumens orcavities. The electronic circuit components of the device are enclosedby an inert indigestible housing (e.g. glass housing) that passesthrough the body internally. Other examples include an ingestible datarecorder capsule medical device. The electronic circuits of thedisclosed device (e.g. sensor, recorder, battery etc.) are housed in acapsule made of inert materials.

In other examples, fragile radio frequency identification (RFID) tagsare used in drug ingestion monitoring applications. In order for theRFID tags to be operational, each requires an internal power supply. TheRFID tags are antenna structures that are configured to transmit aradio-frequency signal through the body.

The problem these existing devices pose is that the power source isinternal to device and such power sources are costly to produce andpotentially harmful to the surrounding environment if the power sourceleaks or is damaged. Additionally, having antennas extending from thedevice is a concern as related to the antennas getting damaged orcausing a problem when the device is used in-vivo. Therefore, what isneeded is suitable system with circuitry that eliminates the need for aninternal power source and antennas.

SUMMARY

The present disclosure includes a system for producing a uniquesignature that indicates the occurrence of an event. The system includescircuitry and components that can be placed within certain environmentsthat include a conducting fluid. One example of such an environment isinside a container that houses the conducting fluid, such as a sealedbag with a solution, which includes an IV bag. Another example is withinthe body of a living organism, such as an animal or a human. The systemsare ingestible and/or digestible or partially digestible. The systemincludes dissimilar materials positioned on the framework such that whena conducting fluid comes into contact with the dissimilar materials, avoltage potential difference is created. The voltage potentialdifference, and hence the voltage, is used to power up control logicthat is positioned within the framework. Ions or current flows from thefirst dissimilar material to the second dissimilar material via thecontrol logic and then through the conducting fluid to complete acircuit. The control logic controls the conductance between the twodissimilar materials and, hence, controls or modulates the conductance.

As the ingestible circuitry is made up of ingestible, and evendigestible, components, the ingestible circuitry results in little, ifany, unwanted side effects, even when employed in chronic situations.Examples of the range of components that may be included are: logicand/or memory elements; effectors; a signal transmission element; and apassive element, such as a resistor or inductor. The one or morecomponents on the surface of the support may be laid out in anyconvenient configuration. Where two or more components are present onthe surface of the solid support, interconnects may be provided. All ofthe components and the support of the ingestible circuitry areingestible, and in certain instances digestible or partially digestible.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a pharmaceutical product with an event indicator systemaccording to the teaching of the present invention, wherein the productand the event indicator system combination are within the body.

FIG. 2A shows the pharmaceutical product of FIG. 1 with the eventindicator system on the exterior of the pharmaceutical product.

FIG. 2B shows the pharmaceutical product of FIG. 1 with the eventindicator system positioned inside the pharmaceutical product.

FIG. 3 is a block diagram representation of one aspect of the eventindicator system with dissimilar metals positioned on opposite ends.

FIG. 4 is a block diagram representation of another aspect of the eventindicator system with dissimilar metals positioned on the same end andseparated by a non-conducting material.

FIG. 5 shows ionic transfer or the current path through a conductingfluid when the event indicator system of FIG. 3 is in contact withconducting liquid and in an active state.

FIG. 5A shows an exploded view of the surface of dissimilar materials ofFIG. 5.

FIG. 5B shows the event indicator system of FIG. 5 with a pH sensorunit.

FIG. 6 is a block diagram illustration of one aspect of the controldevice used in the system of FIGS. 3 and 4.

DETAILED DESCRIPTION

The present disclosure includes multiple embodiments for indicating theoccurrence of an event. As described in more detail below, a system ofthe present invention is used with a conducting fluid to indicate theevent marked by contact between the conducting fluid and the system. Forexample, the system of the present disclosure may be used withpharmaceutical product and the event that is indicated is when theproduct is taken or ingested. The term “ingested” or “ingest” or“ingesting” is understood to mean any introduction of the systeminternal to the body. For example, ingesting includes simply placing thesystem in the mouth all the way to the descending colon. Thus, the termingesting refers to any instant in time when the system is introduced toan environment that contains a conducting fluid. Another example wouldbe a situation when a non-conducting fluid is mixed with a conductingfluid. In such a situation the system would be present in thenon-conduction fluid and when the two fluids are mixed, the system comesinto contact with the conducting fluid and the system is activated. Yetanother example would be the situation when the presence of certainconducting fluids needed to be detected. In such instances, the presenceof the system, which would be activated, within the conducting fluidcould be detected and, hence, the presence of the respective fluid wouldbe detected.

Referring again to the instance where the system is used with theproduct that is ingested by the living organism, when the product thatincludes the system is taken or ingested, the device comes into contactwith the conducting liquid of the body. When the system of the presentinvention comes into contact with the body fluid, a voltage potential iscreated and the system is activated. A portion of the power source isprovided by the device, while another portion of the power source isprovided by the conducting fluid, which is discussed in detail below.

Referring now to FIG. 1, an ingestible product 14 that includes a systemof the present invention is shown inside the body. The product 14 isconfigured as an orally ingestible pharmaceutical formulation in theform of a pill or capsule. Upon ingestion, the pill moves to thestomach. Upon reaching the stomach, the product 14 is in contact withstomach fluid 18 and undergoes a chemical reaction with the variousmaterials in the stomach fluid 18, such as hydrochloric acid and otherdigestive agents. The system of the present invention is discussed inreference to a pharmaceutical environment. However, the scope of thepresent invention is not limited thereby. The present invention can beused in any environment where a conducting fluid is present or becomespresent through mixing of two or more components that result in aconducting liquid.

Referring now to FIG. 2A, a pharmaceutical product 10, similar to theproduct 14 of FIG. 1, is shown with a system 12, such as an ingestibleevent marker or an ionic emission module. The scope of the presentinvention is not limited by the shape or type of the product 10. Forexample, it will be clear to one skilled in the art that the product 10can be a capsule, a time-release oral dosage, a tablet, a gel cap, asub-lingual tablet, or any oral dosage product that can be combined withthe system 12. In the referenced embodiment, the product 10 has thesystem 12 secured to the exterior using known methods of securingmicro-devices to the exterior of pharmaceutical products. Example ofmethods for securing the micro-device to the product is disclosed inU.S. Provisional Application No. 61/142,849 filed on Jan. 1, 2009 andentitled “HIGH-THROUGHPUT PRODUCTION OF INGESTIBLE EVENT MARKERS” aswell as U.S. Provisional Application No. 61/177,611 filed on May 12,2009 and entitled “INGESTIBLE EVENT MARKERS COMPRISING AN IDENTIFIER ANDAN INGESTIBLE COMPONENT”, the entire disclosure of each is incorporatedherein by reference. Once ingested, the system 12 comes into contactwith body liquids and the system 12 is activated. The system 12 uses thevoltage potential difference to power up and thereafter modulatesconductance to create a unique and identifiable current signature. Uponactivation, the system 12 controls the conductance and, hence, currentflow to produce the current signature.

There are various reasons for delaying the activation of the system 12.In order to delay the activation of the system 12, the system 12 may becoated with a shielding material or protective layer. The layer isdissolved over a period of time, thereby allowing the system 12 to beactivated when the product 10 has reached a target location.

Referring now to FIG. 2B, a pharmaceutical product 20, similar to theproduct 14 of FIG. 1, is shown with a system 22, such as an ingestibleevent marker or an identifiable emission module. The scope of thepresent invention is not limited by the environment to which the system22 is introduced. For example, the system 22 can be enclosed in acapsule that is taken in addition to/independently from thepharmaceutical product. The capsule may be simply a carrier for thesystem 22 and may not contain any product. Furthermore, the scope of thepresent invention is not limited by the shape or type of product 20. Forexample, it will be clear to one skilled in the art that the product 20can be a capsule, a time-release oral dosage, a tablet, a gel capsule, asub-lingual tablet, or any oral dosage product. In the referencedembodiment, the product 20 has the system 22 positioned inside orsecured to the interior of the product 20. In one embodiment, the system22 is secured to the interior wall of the product 20. When the system 22is positioned inside a gel capsule, then the content of the gel capsuleis a non-conducting gel-liquid. On the other hand, if the content of thegel capsule is a conducting gel-liquid, then in an alternativeembodiment, the system 22 is coated with a protective cover to preventunwanted activation by the gel capsule content. If the content of thecapsule is a dry powder or microspheres, then the system 22 ispositioned or placed within the capsule. If the product 20 is a tabletor hard pill, then the system 22 is held in place inside the tablet.Once ingested, the product 20 containing the system 22 is dissolved. Thesystem 22 comes into contact with body liquids and the system 22 isactivated. Depending on the product 20, the system 22 may be positionedin either a near-central or near-perimeter position depending on thedesired activation delay between the time of initial ingestion andactivation of the system 22. For example, a central position for thesystem 22 means that it will take longer for the system 22 to be incontact with the conducting liquid and, hence, it will take longer forthe system 22 to be activated. Therefore, it will take longer for theoccurrence of the event to be detected.

Referring now to FIG. 3, in one embodiment, the systems 12 and 22 ofFIGS. 2A and 2B, respectively, are shown in more detail as system 30.The system 30 can be used in association with any pharmaceuticalproduct, as mentioned above, to determine when a patient takes thepharmaceutical product. As indicated above, the scope of the presentinvention is not limited by the environment and the product that is usedwith the system 30. For example, the system 30 may be placed within acapsule and the capsule is placed within the conducting liquid. Thecapsule would then dissolve over a period of time and release the system30 into the conducting liquid. Thus, in one embodiment, the capsulewould contain the system 30 and no product. Such a capsule may then beused in any environment where a conducting liquid is present and withany product. For example, the capsule may be dropped into a containerfilled with jet fuel, salt water, tomato sauce, motor oil, or anysimilar product. Additionally, the capsule containing the system 30 maybe ingested at the same time that any pharmaceutical product is ingestedin order to record the occurrence of the event, such as when the productwas taken.

In the specific example of the system 30 combined with thepharmaceutical product, as the product or pill is ingested, the system30 is activated. The system 30 controls conductance to produce a uniquecurrent signature that is detected, thereby signifying that thepharmaceutical product has been taken. The system 30 includes aframework 32. The framework 32 is a chassis for the system 30 andmultiple components are attached to, deposited upon, or secured to theframework 32. In this embodiment of the system 30, a digestible material34 is physically associated with the framework 32. The material 34 maybe chemically deposited on, evaporated onto, secured to, or built-up onthe framework all of which may be referred to herein as “deposit” withrespect to the framework 32. The material 34 is deposited on one side ofthe framework 32. The materials of interest that can be used as material34 include, but are not limited to: Cu or CuI. The material 34 isdeposited by physical vapor deposition, electrodeposition, or plasmadeposition, among other protocols. The material 34 may be from about0.05 to about 500 μm thick, such as from about 5 to about 100 μm thick.The shape is controlled by shadow mask deposition, or photolithographyand etching. Additionally, even though only one region is shown fordepositing the material, each system 30 may contain two or moreelectrically unique regions where the material 34 may be deposited, asdesired.

At a different side, which is the opposite side as shown in FIG. 3,another digestible material 36 is deposited, such that materials 34 and36 are dissimilar. Although not shown, the different side selected maybe the side next to the side selected for the material 34. The scope ofthe present invention is not limited by the side selected and the term“different side” can mean any of the multiple sides that are differentfrom the first selected side. Furthermore, even though the shape of thesystem is shown as a square, the shape maybe any geometrically suitableshape. Material 34 and 36 are selected such that they produce a voltagepotential difference when the system 30 is in contact with conductingliquid, such as body fluids. The materials of interest for material 36include, but are not limited to: Mg, Zn, or other electronegativemetals. As indicated above with respect to the material 34, the material36 may be chemically deposited on, evaporated onto, secured to, orbuilt-up on the framework. Also, an adhesion layer may be necessary tohelp the material 36 (as well as material 34 when needed) to adhere tothe framework 32. Typical adhesion layers for the material 36 are Ti,TiW, Cr or similar material. Anode material and the adhesion layer maybe deposited by physical vapor deposition, electrodeposition or plasmadeposition. The material 36 may be from about 0.05 to about 500 μmthick, such as from about 5 to about 100 μm thick. However, the scope ofthe present invention is not limited by the thickness of any of thematerials nor by the type of process used to deposit or secure thematerials to the framework 32.

According to the disclosure set forth, the materials 34 and 36 can beany pair of materials with different electrochemical potentials.Additionally, in the embodiments wherein the system 30 is used in-vivo,the materials 34 and 36 may be vitamins that can be absorbed. Morespecifically, the materials 34 and 36 can be made of any two materialsappropriate for the environment in which the system 30 will beoperating. For example, when used with an ingestible product, thematerials 34 and 36 are any pair of materials with differentelectrochemical potentials that are ingestible. An illustrative exampleincludes the instance when the system 30 is in contact with an ionicsolution, such as stomach acids. Suitable materials are not restrictedto metals, and in certain embodiments the paired materials are chosenfrom metals and non-metals, e.g., a pair made up of a metal (such as Mg)and a salt (such as CuCl or CuI). With respect to the active electrodematerials, any pairing of substances—metals, salts, or intercalationcompounds—with suitably different electrochemical potentials (voltage)and low interfacial resistance are suitable.

Materials and pairings of interest include, but are not limited to,those reported in Table 1 below. In one embodiment, one or both of themetals may be doped with a non-metal, e.g., to enhance the voltagepotential created between the materials as they come into contact with aconducting liquid. Non-metals that may be used as doping agents incertain embodiments include, but are not limited to: sulfur, iodine andthe like. In another embodiment, the materials are copper iodine (CuI)as the anode and magnesium (Mg) as the cathode. Embodiments of thepresent invention use electrode materials that are not harmful to thehuman body.

TABLE 1 Anode Cathode Metals Magnesium, Zinc Sodium (†), Lithium (†)Iron Salts Copper salts: iodide, chloride, bromide, sulfate, formate,(other anions possible) Fe³⁺ salts: e.g. orthophosphate, pyrophosphate,(other anions possible) Oxygen (††) on platinum, gold or other catalyticsurfaces Intercalation Graphite with Li, Vanadium oxide compounds K, Ca,Na, Mg Manganese oxide

Thus, when the system 30 is in contact with the conducting liquid, acurrent path, an example is shown in FIG. 5, is formed through theconducting liquid between material 34 and 36. A control device 38 issecured to the framework 32 and electrically coupled to the materials 34and 36. The control device 38 includes electronic circuitry, for examplecontrol logic that is capable of controlling and altering theconductance between the materials 34 and 36.

The voltage potential created between the materials 34 and 36 providesthe power for operating the system as well as produces the current flowthrough the conducting fluid and the system. In one embodiment, thesystem operates in direct current mode. In an alternative embodiment,the system controls the direction of the current so that the directionof current is reversed in a cyclic manner, similar to alternatingcurrent. As the system reaches the conducting fluid or the electrolyte,where the fluid or electrolyte component is provided by a physiologicalfluid, e.g., stomach acid, the path for current flow between thematerials 34 and 36 is completed external to the system 30; the currentpath through the system 30 is controlled by the control device 38.Completion of the current path allows for the current to flow and inturn a receiver, not shown, can detect the presence of the current andrecognize that the system 30 has been activate and the desired event isoccurring or has occurred.

In one embodiment, the two materials 34 and 36 are similar in functionto the two electrodes needed for a direct current power source, such asa battery. The conducting liquid acts as the electrolyte needed tocomplete the power source. The completed power source described isdefined by the physical chemical reaction between the materials 34 and36 of the system 30 and the surrounding fluids of the body. Thecompleted power source may be viewed as a power source that exploitsreverse electrolysis in an ionic or a conduction solution such asgastric fluid, blood, or other bodily fluids and some tissues.Additionally, the environment may be something other than a body and theliquid may be any conducting liquid. For example, the conducting fluidmay be salt water or a metallic based paint.

In certain embodiments, these two materials are shielded from thesurrounding environment by an additional layer of material. Accordingly,when the shield is dissolved and the two dissimilar materials areexposed to the target site, a voltage potential is generated.

In certain embodiments, the complete power source or supply is one thatis made up of active electrode materials, electrolytes, and inactivematerials, such as current collectors, packaging, etc. The activematerials are any pair of materials with different electrochemicalpotentials. Suitable materials are not restricted to metals, and incertain embodiments the paired materials are chosen from metals andnon-metals, e.g., a pair made up of a metal (such as Mg) and a salt(such as CuI). With respect to the active electrode materials, anypairing of substances—metals, salts, or intercalation compounds—withsuitably different electrochemical potentials (voltage) and lowinterfacial resistance are suitable.

A variety of different materials may be employed as the materials thatform the electrodes. In certain embodiments, electrode materials arechosen to provide for a voltage upon contact with the targetphysiological site, e.g., the stomach, sufficient to drive the system ofthe identifier. In certain embodiments, the voltage provided by theelectrode materials upon contact of the metals of the power source withthe target physiological site is 0.001 V or higher, including 0.01 V orhigher, such as 0.1 V or higher, e.g., 0.3 V or higher, including 0.5volts or higher, and including 1.0 volts or higher, where in certainembodiments, the voltage ranges from about 0.001 to about 10 volts, suchas from about 0.01 to about 10 V.

Referring again to FIG. 3, the materials 34 and 36 provide the voltagepotential to activate the control device 38. Once the control device 38is activated or powered up, the control device 38 can alter conductancebetween the materials 34 and 36 in a unique manner. By altering theconductance between materials 34 and 36, the control device 38 iscapable of controlling the magnitude of the current through theconducting liquid that surrounds the system 30. This produces a uniquecurrent signature that can be detected and measured by a receiver (notshown), which can be positioned internal or external to the body. Inaddition to controlling the magnitude of the current path between thematerials, non-conducting materials, membrane, or “skirt” are used toincrease the “length” of the current path and, hence, act to boost theconductance path, as disclosed in the U.S. patent application Ser. No.12/238,345 entitled, “In-Body Device with Virtual Dipole SignalAmplification” filed Sep. 25, 2008, the entire content of which isincorporated herein by reference. Alternatively, throughout thedisclosure herein, the terms “non-conducting material”, “membrane”, and“skirt” are interchangeably with the term “current path extender”without impacting the scope or the present embodiments and the claimsherein. The skirt, shown in portion at 35 and 37, respectively, may beassociated with, e.g., secured to, the framework 32. Various shapes andconfigurations for the skirt are contemplated as within the scope of thepresent invention. For example, the system 30 may be surrounded entirelyor partially by the skirt and the skirt maybe positioned along a centralaxis of the system 30 or off-center relative to a central axis. Thus,the scope of the present invention as claimed herein is not limited bythe shape or size of the skirt. Furthermore, in other embodiments, thematerials 34 and 36 may be separated by one skirt that is positioned inany defined region between the materials 34 and 36.

Referring now to FIG. 4, in another embodiment, the systems 12 and 22 ofFIGS. 2A and 2B, respectively, are shown in more detail as system 40.The system 40 includes a framework 42. The framework 42 is similar tothe framework 32 of FIG. 3. In this embodiment of the system 40, adigestible or dissolvable material 44 is deposited on a portion of oneside of the framework 42. At a different portion of the same side of theframework 42, another digestible material 46 is deposited, such thatmaterials 44 and 46 are dissimilar. More specifically, material 44 and46 are selected such that they form a voltage potential difference whenin contact with a conducting liquid, such as body fluids. Thus, when thesystem 40 is in contact with and/or partially in contact with theconducting liquid, then a current path, an example is shown in FIG. 5,is formed through the conducting liquid between material 44 and 46. Acontrol device 48 is secured to the framework 42 and electricallycoupled to the materials 44 and 46. The control device 48 includeselectronic circuitry that is capable of controlling part of theconductance path between the materials 44 and 46. The materials 44 and46 are separated by a non-conducting skirt 49. Various examples of theskirt 49 are disclosed in U.S. Provisional Application No. 61/173,511filed on Apr. 28, 2009 and entitled “HIGHLY RELIABLE INGESTIBLE EVENTMARKERS AND METHODS OF USING SAME” and U.S. Provisional Application No.61/173,564 filed on Apr. 28, 2009 and entitled “INGESTIBLE EVENT MARKERSHAVING SIGNAL AMPLIFIERS THAT COMPRISE AN ACTIVE AGENT”; as well as U.S.application Ser. No. 12/238,345 filed Sep. 25, 2008 and entitled“IN-BODY DEVICE WITH VIRTUAL DIPOLE SIGNAL AMPLIFICATION”; the entiredisclosure of each is incorporated herein by reference.

Once the control device 48 is activated or powered up, the controldevice 48 can alter conductance between the materials 44 and 46. Thus,the control device 48 is capable of controlling the magnitude of thecurrent through the conducting liquid that surrounds the system 40. Asindicated above with respect to system 30, a unique current signaturethat is associated with the system 40 can be detected by a receiver (notshown) to mark the activation of the system 40. In order to increase the“length” of the current path the size of the skirt 49 is altered. Thelonger the current path, the easier it may be for the receiver to detectthe current.

Referring now to FIG. 5, the system 30 of FIG. 3 is shown in anactivated state and in contact with conducting liquid. The system 30 isgrounded through ground contact 52. The system 30 also includes a sensormodule 74, which is described in greater detail with respect to FIG. 6.Ion or current paths 50 between material 34 to material 36 and throughthe conducting fluid in contact with the system 30. The voltagepotential created between the material 34 and 36 is created throughchemical reactions between materials 34/36 and the conducting fluid.FIG. 5A shows an exploded view of the surface of the material 34. Thesurface of the material 34 is not planar, but rather an irregularsurface. The irregular surface increases the surface area of thematerial and, hence, the area that comes in contact with the conductingfluid.

In one embodiment, at the surface of the material 34, there is chemicalreaction between the material 34 and the surrounding conducting fluidsuch that mass is released into the conducting fluid. The term “mass” asused herein refers to protons and neutrons that form a substance. Oneexample includes the instant where the material is CuCl and when incontact with the conducting fluid, CuCl becomes Cu (solid) and Cl⁻ insolution. The flow of ions into the conduction fluid is depicted by theion paths 50. In a similar manner, there is a chemical reaction betweenthe material 36 and the surrounding conducting fluid and ions arecaptured by the material 36. The release of ions at the material 34 andcapture of ion by the material 36 is collectively referred to as theionic exchange. The rate of ionic exchange and, hence the ionic emissionrate or flow, is controlled by the control device 38. The control device38 can increase or decrease the rate of ion flow by altering theconductance, which alters the impedance, between the materials 34 and36. Through controlling the ion exchange, the system 30 can encodeinformation in the ionic exchange process. Thus, the system 30 usesionic emission to encode information in the ionic exchange.

The control device 38 can vary the duration of a fixed ionic exchangerate or current flow magnitude while keeping the rate or magnitude nearconstant, similar to when the frequency is modulated and the amplitudeis constant. Also, the control device 38 can vary the level of the ionicexchange rate or the magnitude of the current flow while keeping theduration near constant. Thus, using various combinations of changes induration and altering the rate or magnitude, the control device 38encodes information in the current flow or the ionic exchange. Forexample, the control device 38 may use, but is not limited to any of thefollowing techniques namely, Binary Phase-Shift Keying (PSK), Frequencymodulation, Amplitude modulation, on-off keying, and PSK with on-offkeying.

As indicated above, the various embodiments disclosed herein, such assystems 30 and 40 of FIGS. 3 and 4, respectively, include electroniccomponents as part of the control device 38 or the control device 48.Components that may be present include but are not limited to: logicand/or memory elements, an integrated circuit, an inductor, a resistor,and sensors for measuring various parameters. Each component may besecured to the framework and/or to another component. The components onthe surface of the support may be laid out in any convenientconfiguration. Where two or more components are present on the surfaceof the solid support, interconnects may be provided.

As indicated above, the system, such as system 30 and 40, control theconductance between the dissimilar materials and, hence, the rate ofionic exchange or the current flow. Through altering the conductance ina specific manner the system is capable of encoding information in theionic exchange and the current signature. The ionic exchange or thecurrent signature is used to uniquely identify the specific system.Additionally, the systems 30 and 40 are capable of producing variousdifferent unique exchanges or signatures and, thus, provide additionalinformation. For example, a second current signature based on a secondconductance alteration pattern may be used to provide additionalinformation, which information may be related to the physicalenvironment. To further illustrate, a first current signature may be avery low current state that maintains an oscillator on the chip and asecond current signature may be a current state at least a factor of tenhigher than the current state associated with the first currentsignature.

Referring now to FIG. 6, a block diagram representation of the controldevice 38 is shown. The device 30 includes a control module 62, acounter or clock 64, and a memory 66. Additionally, the device 38 isshown to include a sensor module 72 as well as the sensor module 74,which was referenced in FIG. 5. The control module 62 has an input 68electrically coupled to the material 34 and an output 70 electricallycoupled to the material 36. The control module 62, the clock 64, thememory 66, and the sensor modules 72/74 also have power inputs (some notshown). The power for each of these components is supplied by thevoltage potential produced by the chemical reaction between materials 34and 36 and the conducting fluid, when the system 30 is in contact withthe conducting fluid. The control module 62 controls the conductancethrough logic that alters the overall impedance of the system 30. Thecontrol module 62 is electrically coupled to the clock 64. The clock 64provides a clock cycle to the control module 62. Based upon theprogrammed characteristics of the control module 62, when a set numberof clock cycles have passed, the control module 62 alters theconductance characteristics between materials 34 and 36. This cycle isrepeated and thereby the control device 38 produces a unique currentsignature characteristic. The control module 62 is also electricallycoupled to the memory 66. Both the clock 64 and the memory 66 arepowered by the voltage potential created between the materials 34 and36.

The control module 62 is also electrically coupled to and incommunication with the sensor modules 72 and 74. In the embodimentshown, the sensor module 72 is part of the control device 38 and thesensor module 74 is a separate component. In alternative embodiments,either one of the sensor modules 72 and 74 can be used without the otherand the scope of the present invention is not limited by the structuralor functional location of the sensor modules 72 or 74. Additionally, anycomponent of the system 30 may be functionally or structurally moved,combined, or repositioned without limiting the scope of the presentinvention as claimed. Thus, it is possible to have one single structure,for example a processor, which is designed to perform the functions ofall of the following modules: the control module 62, the clock 64, thememory 66, and the sensor module 72 or 74. On the other hand, it is alsowithin the scope of the present invention to have each of thesefunctional components located in independent structures that are linkedelectrically and able to communicate.

Referring again to FIG. 6, the sensor modules 72 or 74 can include anyof the following sensors: temperature, pressure, pH level, andconductivity. In one embodiment, the sensor modules 72 or 74 gatherinformation from the environment and communicate the analog informationto the control module 62. The control module then converts the analoginformation to digital information and the digital information isencoded in the current flow or the rate of the transfer of mass thatproduces the ionic flow. In another embodiment, the sensor modules 72 or74 gather information from the environment and convert the analoginformation to digital information and then communicate the digitalinformation to control module 62. In the embodiment shown in FIG. 5, thesensor modules 74 is shown as being electrically coupled to the material34 and 36 as well as the control device 38. In another embodiment, asshown in FIG. 6, the sensor module 74 is electrically coupled to thecontrol device 38 at connection 78. The connection 78 acts as both asource for power supply to the sensor module 74 and a communicationchannel between the sensor module 74 and the control device 38.

Referring now to FIG. 5B, the system 30 includes a pH sensor module 76connected to a material 39, which is selected in accordance with thespecific type of sensing function being performed. The pH sensor module76 is also connected to the control device 38. The material 39 iselectrically isolated from the material 34 by a non-conductive barrier55. In one embodiment, the material 39 is platinum. In operation, the pHsensor module 76 uses the voltage potential difference between thematerials 34/36. The pH sensor module 76 measures the voltage potentialdifference between the material 34 and the material 39 and records thatvalue for later comparison. The pH sensor module 76 also measures thevoltage potential difference between the material 39 and the material 36and records that value for later comparison. The pH sensor module 76calculates the pH level of the surrounding environment using the voltagepotential values. The pH sensor module 76 provides that information tothe control device 38. The control device 38 varies the rate of thetransfer of mass that produces the ionic transfer and the current flowto encode the information relevant to the pH level in the ionictransfer, which can be detected by a receiver (not shown). Thus, thesystem 30 can determine and provide the information related to the pHlevel to a source external to the environment.

As indicated above, the control device 38 can be programmed in advanceto output a pre-defined current signature. In another embodiment, thesystem can include a receiver system that can receive programminginformation when the system is activated. In another embodiment, notshown, the switch 64 and the memory 66 can be combined into one device.

In addition to the above components, the system 30 may also include oneor other electronic components. Electrical components of interestinclude, but are not limited to: additional logic and/or memoryelements, e.g., in the form of an integrated circuit; a power regulationdevice, e.g., battery, fuel cell or capacitor; a sensor, a stimulator,etc.; a signal transmission element, e.g., in the form of an antenna,electrode, coil, etc.; a passive element, e.g., an inductor, resistor,etc.

In certain embodiments, the ingestible circuitry includes a coatinglayer. The purpose of this coating layer can vary, e.g., to protect thecircuitry, the chip and/or the battery, or any components duringprocessing, during storage, or even during ingestion. In such instances,a coating on top of the circuitry may be included. Also of interest arecoatings that are designed to protect the ingestible circuitry duringstorage, but dissolve immediately during use. For example, coatings thatdissolve upon contact with an aqueous fluid, e.g. stomach fluid, or theconducting fluid as referenced above. Also of interest are protectiveprocessing coatings that are employed to allow the use of processingsteps that would otherwise damage certain components of the device. Forexample, in embodiments where a chip with dissimilar material depositedon the top and bottom is produced, the product needs to be diced.However, the dicing process can scratch off the dissimilar material, andalso there might be liquid involved which would cause the dissimilarmaterials to discharge or dissolve. In such instances, a protectivecoating on the materials prevents mechanical or liquid contact with thecomponent during processing can be employed. Another purpose of thedissolvable coatings may be to delay activation of the device. Forexample, the coating that sits on the dissimilar material and takes acertain period of time, e.g., five minutes, to dissolve upon contactwith stomach fluid may be employed. The coating can also be anenvironmentally sensitive coating, e.g., a temperature or pH sensitivecoating, or other chemically sensitive coating that provides fordissolution in a controlled fashion and allows one to activate thedevice when desired. Coatings that survive the stomach but dissolve inthe intestine are also of interest, e.g., where one desires to delayactivation until the device leaves the stomach. An example of such acoating is a polymer that is insoluble at low pH, but becomes soluble ata higher pH. Also of interest are pharmaceutical formulation protectivecoatings, e.g., a gel cap liquid protective coating that prevents thecircuit from being activated by liquid of the gel cap.

Identifiers of interest include two dissimilar electrochemicalmaterials, which act similar to the electrodes (e.g., anode and cathode)of a power source. The reference to an electrode or anode or cathode areused here merely as illustrative examples. The scope of the presentinvention is not limited by the label used and includes the embodimentwherein the voltage potential is created between two dissimilarmaterials. Thus, when reference is made to an electrode, anode, orcathode it is intended as a reference to a voltage potential createdbetween two dissimilar materials.

When the materials are exposed and come into contact with the bodyfluid, such as stomach acid or other types of fluid (either alone or incombination with a dried conductive medium precursor), a potentialdifference, that is, a voltage, is generated between the electrodes as aresult of the respective oxidation and reduction reactions incurred tothe two electrode materials. A voltaic cell, or battery, can thereby beproduced. Accordingly, in embodiments of the invention, such powersupplies are configured such that when the two dissimilar materials areexposed to the target site, e.g., the stomach, the digestive tract,etc., a voltage is generated.

In certain embodiments, one or both of the metals may be doped with anon-metal, e.g., to enhance the voltage output of the battery.Non-metals that may be used as doping agents in certain embodimentsinclude, but are not limited to: sulfur, iodine and the like.

It is to be understood that this invention is not limited to particularembodiments or aspects described, as such may vary. It is also to beunderstood that the terminology used herein is for the purpose ofdescribing particular embodiments only, and is not intended to belimiting, since the scope of the present invention will be limited onlyby the appended claims.

Where a range of values is provided, it is understood that eachintervening value, to the tenth of the unit of the lower limit unlessthe context clearly dictates otherwise, between the upper and lowerlimit of that range and any other stated or intervening value in thatstated range, is encompassed within the invention. The upper and lowerlimits of these smaller ranges may independently be included in thesmaller ranges and are also encompassed within the invention, subject toany specifically excluded limit in the stated range. Where the statedrange includes one or both of the limits, ranges excluding either orboth of those included limits are also included in the invention.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although any methods andmaterials similar or equivalent to those described herein can also beused in the practice or testing of the present invention, representativeillustrative methods and materials are now described.

All publications and patents cited in this specification are hereinincorporated by reference as if each individual publication or patentwere specifically and individually indicated to be incorporated byreference and are incorporated herein by reference to disclose anddescribe the methods and/or materials in connection with which thepublications are cited. The citation of any publication is for itsdisclosure prior to the filing date and should not be construed as anadmission that the present invention is not entitled to antedate suchpublication by virtue of prior invention. Further, the dates ofpublication provided may be different from the actual publication dateswhich may need to be independently confirmed.

It is noted that, as used herein and in the appended claims, thesingular forms “a”, “an”, and “the” include plural referents unless thecontext clearly dictates otherwise. It is further noted that the claimsmay be drafted to exclude any optional element. As such, this statementis intended to serve as antecedent basis for use of such exclusiveterminology as “solely,” “only” and the like in connection with therecitation of claim elements, or use of a “negative” limitation.

As will be apparent to those of skill in the art upon reading thisdisclosure, each of the individual embodiments described and illustratedherein has discrete components and features which may be readilyseparated from or combined with the features of any of the other severalembodiments without departing from the scope or spirit of the presentinvention. Any recited method can be carried out in the order of eventsrecited or in any other order which is logically possible.

Although the foregoing invention has been described in some detail byway of illustration and example for purposes of clarity ofunderstanding, it is readily apparent to those of ordinary skill in theart in light of the teachings of this invention that certain changes andmodifications may be made thereto without departing from the spirit orscope of the appended claims.

Accordingly, the preceding merely illustrates the principles of theinvention. It will be appreciated that those skilled in the art will beable to devise various arrangements which, although not explicitlydescribed or shown herein, embody the principles of the invention andare included within its spirit and scope. Furthermore, all examples andconditional language recited herein are principally intended to aid thereader in understanding the principles of the invention and the conceptscontributed by the inventors to furthering the art, and are to beconstrued as being without limitation to such specifically recitedexamples and conditions. Moreover, all statements herein recitingprinciples, aspects, and embodiments of the invention as well asspecific examples thereof, are intended to encompass both structural andfunctional equivalents thereof. Additionally, it is intended that suchequivalents include both currently known equivalents and equivalentsdeveloped in the future, i.e., any elements developed that perform thesame function, regardless of structure. The scope of the presentinvention, therefore, is not intended to be limited to the exemplaryembodiments shown and described herein. Rather, the scope and spirit ofpresent invention is embodied by the appended claims.

What is claimed is:
 1. A composition comprising: an ingestible componentcomprising an ingestible event marker and a pharmaceutically acceptablecarrier; and an external layer enclosing the ingestible component toprovide a protective barrier for the ingestible component, wherein atleast a portion of the external layer is configured to dissolve when theexternal layer is in contact with a liquid; wherein the ingestible eventmarker comprises: a control device; and a partial power sourcecomprising first and second electrodes formed of dissimilarelectrochemical materials configured to contact an electricallyconductive fluid and generate a voltage to energize the ingestible eventmarker; and wherein the energized ingestible event marker is configuredto produce a conductive current flow through the electrically conductivefluid; and wherein the control device is configured to control theconductive current flow.
 2. The composition according to claim 1,wherein the external layer comprises a homogeneous layer of a singlematerial.
 3. The composition according to claim 1, wherein the externallayer comprises two or more distinct materials.
 4. The compositionaccording to claim 3, wherein the two or more distinct materials arepresent as a multilayer structure.
 5. The composition according to claim1, wherein the external layer is configured to provide aqueous liquidpassage through the external layer upon contact of the composition withan aqueous liquid.
 6. The composition according to claim 1, wherein theexternal layer is configured to protect the ingestible component in adicing process.
 7. The composition according to claim 1, wherein theexternal layer is configured to dissolve in five or more minutes uponbeing in contact with the liquid.
 8. The composition according to claim1, wherein the external layer is environmentally sensitive.
 9. Thecomposition according to claim 8, wherein the external layer istemperature sensitive.
 10. The composition according to claim 8, whereinthe external layer is pH sensitive.